First, this is definitely not a perfect, or even amazing series. It's definitely not terrible either... The author has a very good writing style for the most part, he captures a lot of the dramatic irony allowed by the dual persona and he has the patience and detail to go through different aspects of the world and life of the character. After the first volume, I was quite ready to give this series a 10. By volume 11, however, I dropped the series, and my 7 rating is just because I did enjoy reading a fair amount of it. Note that I read the original, so I can't comment on the translation.
I'm going to start with this, since it seems to be the topic of most of the debates here. To be quite honest, I don't really care if a reincarnated character has a -implied mostly- h-scene with a girl his own age, in his new body. Part of the idea of reincarnation is that you should be dealing with new social circumstances, hormonal changes, age context and it's not as if he's taking advantage of little girls in order to injure them - he was in reciprocal romantic relationships with them...
Except that the author doesn't really write it this way... there are these really irksome, misogynist ways that the author objectifies girls in the series. If it was to represent a certain characterisation or if it was just one aspect of his descriptions, then I wouldn't be quite so annoyed, but it's constant, in pretty much every single chapter, right from the beginning. There is very little romance involved, since all the relationships are driven by the protagonist's arousal rather than any actual caring or interest in the thought, culture and lifestyle of other characters.
Now, before inferring that I mean the author is a misogynistic pervert or something, it's worth taking a step back and seeing where this comes from. The author really treats women in his story not like actual people, but like anime characters from those moe subculture shows that I admittedly don't care for... If you like moe archetypes such as the slightly tomboyish but completely devoted childhood friend, the tsundere noble girl, the clumsy library girl, (and some hentai archetypes like the slave-elf, yeah, that one appears later on too...), oh, don't forget the maid and the little sister, then you'll have no problem with the harem women in this series, and you'll probably think little of the characterisation of them, since, well, they whole point is that they are not like intimidating irl girls who might actually want to have a relationship with someone other than the MC or not ever show their dere side to you (oh horror). Just don't expect actual 'relationship' to the relationships, it's more that the MC 'wins' them. No sharing of his own emotions or life stories, no actual trust, he might teach them things, but never actually learns from them, nothing that would be remotely relatable to real relationships...
Also, may I mention that there are almost no male characters in this series. I don't mean none, just none that stand out. I was actually quite excited when the MC made his first childhood friend because I thought it was a boy... until we learn it isn't... After that, there are hardly any male characters (other than his father, who plays a semi-important role) until the doll otaku and another character (trying to avoid spoilers...) who become his proteges later on. Even in those arcs though, there's just a lack of significance of the male characters... the world being made here is harem genre, but I guess if I criticise this series for it, i should at least point out many other series lately are way way worse...
But, the author isn't stupid, just brainwashed by this way of seeing society, so he actually manages to make some character development, makes the women tough enough to fend for themselves, and some of the best parts of the novels are when he switches the perspective to particular side characters/girls' perspectives, which he does every so often, and he actually manages to bring forth compelling psychologies when he does that.
And, the main character isn't actually all that badly made. Besides his comments on women (which are too often, unfortunately), he's pretty decent. He has a complex past, he tries his best to do fun things. He is a total cheat character out of any run-of-the-mill shounen manga, but there are defined limits to his powers and he generally thinks about his actions, when he's not reeling from unexpected situations where you seem him desperately trying to recover from unfortunate incidents. This puts this series at least on 'good' level compared to the dozens of ridiculous stories coming out of this web novel industry lately that, once you get to chapter 2 or 3, the main character is vying for strongest in the universe...
Another selling point of this series is the complexity of the world. It has a reasonably developed magic system, by no means original, but well described and elaborated, it has an actual world map, with different peoples and cultures, again, nothing original, but he gives traditional fantasy (and anime) cliches his own spins, he has some politics and cultural clashes going on that the characters interact with, some historical mythology. Most of all, I enjoyed his early representation of language - although he doesn't make anything particularly complex, we finally have a fantasy world where the main character doesn't magically know how to communicate from day 1, but has to learn it... I was annoyed that only took a couple chapters and that he picked up other languages in the space of a few pages, but at least he learned them.
The world, however, starts to break down in explorations of it. Some countries were essentially reduced to the similarity of some of their foodstuffs with japan's foodstuffs - we passed through this country, they had rice! it wasn't as good as Japanese rice - and, of course, despite living in this world for 15 years, by that point, our character had developed no appreciation of his new world's (and mother's) cuisine. (Also the country of our doll maniac, which I was sceptical of, but he isn't so terrible a character in the end).
There is also too much video game influence in his description of the world... for my taste anyway. Note that I'd be fine with this if it was a novel about a video game like SAO or Log Horizon, but this isn't a video game based world. Nevertheless, the way the author demonstrates learning is by ranks of skills. The skills are all discrete, everyone uses the same fireball spell or slash skill. The wild is all random encounter monsters, essentially, that wink into existence in places with enough 'magical concentration', and although there is some historical background to the world, it is all the legends of so and so, who will have a direct effect on the story, like the usual video game lore...
Most of all, however, the annoyance for me of the game influence is the structure of cities and professions. The author thinks of the world as being based around adventurers who go around killing monsters and picking up drop items (at least they have to peel the hide of things in this world). Of course, the main merchants are 'weapons' and 'armour' shops, main organisations are adventurer and magic guilds, etc... This makes a lot of the world building feel superficial. I should point out that despite the limitations he sets on himself by depending on video game descriptions, he does get out of this mould sometimes, so it's not entirely immature.
Anyway, I still give it a 7, because I quite enjoyed this series. As far as light novels go, it is one of the better ones... but it's still mediocre as far as good writing goes, though it has potential if the author wanted to revise some of his characterisation and world building for the printed version. EDIT: I am told the printed version is the same as the web novel, so no luck there.